short lived cranks

I have worn out my 3rd set of Nimbus Venture 150s. The contact points at the hub wears until the crank is sloppy. When the first set went bad, I thought it was fault for not keeping the bolt tight. But with the second and third set, I check the torque before every ride and any ride over 2 miles I carry the 8mm wrench (just in case). I’m not doing tricks or stunts as I’m not very good at anything other than going long distances in a straight line on a nice smooth paved trail. Anyone else go thru cranks quickly?

Haven’t had that issue. What hub? how long have you had it? Are you using a long handled 8mm, or one attached to a multi-tool? I’m assuming it’s always tight before a ride, so I don’t suspect you aren’t tightening enough. If you have another hub, do the cranks work on that one?

Sounds like your hub has an undersized spline and would benefit from smaller spacers to allow the crank to go on further.

Also are you adding grease to the spline interface when you install the cranks? The grease helps the cranks seat in and not wear.

When I wasn’t using spacers I used to wear out the spline interface on some ISIS cranks, that stopped being the case when I started using spacers.

Hub: Hub is Nimbus ISIS on a 29er. 2 years old.
long handled wrench; not a multi-tool.

After the second set was trashed, I paid a lot more attention to slop in the fresh 3rd set. One crank was tight, the other had noticeable slop. Slop = 0.40 measured at the pedal end. Of course over time it has gotten much worse. I should add that the problem traded sides. The first 2 cranks wore out on the left side (so I was thinking there was a problem with the left side of the hub). Third set: left was tight initially and is still tight. Right crank is wiped out.

I was thinking about adding some liquid shim when the right side first showed slop. However, I didn’t apply the liquid shim as I was afraid the crank would become a permanent feature :astonished:

I’ll revisit the hub and see what spacers are there, measure and see about adjusting the set up. Thanks!

wow, there should be zero slop.

I would take the cranks off and re-install without spacers, check where they end up and fabricate new spacers that would prevent them from going any further onto the spline. Check to make sure the cranks aren’t already bottoming out (pushed all the way on so the bolt is contacting the hub as well as the cranks)

Take them off again and re-install with the new spacers.

If all else fails as a temporary solution I have seen people shim the spline interface with a candy wrapper.

Thanks Eric. I’ll try the spacers first. The candy wrapper idea got me to thinking…while the liquid shim idea was in the right direction, it is probably the wrong stuff. Perhaps I could fashion a shim out of solder or copper and jamb it into the joint like some would insert the candy wrapper. I’ll give her a go tomorrow and let you know how it works out.

Is the hub welded or press-fit? If it’s a press-fit, is it possible that tightening up one crank without one on the other side could pull the spindle through the body/flange assembly slightly? If that happened then you’d never get the other side tight enough to seat properly as the spindle would now be off-center with respect to the rest of the hub.

I could be talking complete nonsense, in which case I’ll go sit in the corner.

OK, so I took the left crank off and examined closely. It seems that the HUB teeth are damaged from the first cranks that came loose. If I remove the spacer and drive the crank further onto the hub, it gets properly tight. However, the resultant gap beneath the bolt head and crank allows the crank to walk outboard and gets sloppy again.

The solder (in lieu of gum wrapper) helps but still not as it should be. The slop at the pedal end is now only 0.100 inches.

Since the hub is to blame, I think I can proceed with the liquid shim idea even if the crank becomes permanently attached to the hub. However, it will be a while before I try liquid shim as I will ride it as-is for now.

What exactly do you mean by this? How are you pushing the crank onto the hub if there is a gap behind the bolt head?

Aracer asked

I wanted to check for slop when the crank is pushed further onto the axle (that portion normally covered by the spacer). There was no slop on the newly exposed portion: the fit was tight.

However, with the spacer removed, the crank can walk outboard back to the end of the axle where it would be sloppy again (because of the damaged teeth on the axle AND the crank).

I tried using solder as a means to tighten up the slop. I cut pieces of solder to compensate for the damaged teeth. Saskatchewanian mentioned using candy wrapper. I figured solder would be better. It wasn’t: didn’t last 0.5 miles and the solder had worked itself out.

Liquid shim came to mind as a solution. I may still go that route but, looking at UDC, it looks like I can replace the hub for $65 USD. Or, trash to whole thing and upgrade to the Oracle or Disc version…mmmmmm. :sunglasses: